| 11. |
- Sabine, Amélie, et al.
(författare)
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Mechanotransduction, PROX1, and FOXC2 cooperate to control connexin37 and calcineurin during lymphatic-valve formation.
- 2012
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Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 22:2
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Tidskriftsartikel (refereegranskat)abstract
- Lymphatic valves are essential for efficient lymphatic transport, but the mechanisms of early lymphatic-valve morphogenesis and the role of biomechanical forces are not well understood. We found that the transcription factors PROX1 and FOXC2, highly expressed from the onset of valve formation, mediate segregation of lymphatic-valve-forming cells and cell mechanosensory responses to shear stress in vitro. Mechanistically, PROX1, FOXC2, and flow coordinately control expression of the gap junction protein connexin37 and activation of calcineurin/NFAT signaling. Connexin37 and calcineurin are required for the assembly and delimitation of lymphatic valve territory during development and for its postnatal maintenance. We propose a model in which regionally increased levels/activation states of transcription factors cooperate with mechanotransduction to induce a discrete cell-signaling pattern and morphogenetic event, such as formation of lymphatic valves. Our results also provide molecular insights into the role of endothelial cell identity in the regulation of vascular mechanotransduction.
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| 12. |
- Sainz-Jaspeado, Miguel, et al.
(författare)
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Palmdelphin Regulates Nuclear Resilience to Mechanical Stress in the Endothelium
- 2021
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Ingår i: Circulation. - : Wolters Kluwer. - 0009-7322 .- 1524-4539. ; 144:20, s. 1629-1645
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Tidskriftsartikel (refereegranskat)abstract
- Background: PALMD (palmdelphin) belongs to the family of paralemmin proteins implicated in cytoskeletal regulation. Single nucleotide polymorphisms in the PALMD locus that result in reduced expression are strong risk factors for development of calcific aortic valve stenosis and predict severity of the disease.Methods: Immunodetection and public database screening showed dominant expression of PALMD in endothelial cells (ECs) in brain and cardiovascular tissues including aortic valves. Mass spectrometry, coimmunoprecipitation, and immunofluorescent staining allowed identification of PALMD partners. The consequence of loss of PALMD expression was assessed in small interferring RNA-treated EC cultures, knockout mice, and human valve samples. RNA sequencing of ECs and transcript arrays on valve samples from an aortic valve study cohort including patients with the single nucleotide polymorphism rs7543130 informed about gene regulatory changes.Results: ECs express the cytosolic PALMD-KKVI splice variant, which associated with RANGAP1 (RAN GTP hydrolyase activating protein 1). RANGAP1 regulates the activity of the GTPase RAN and thereby nucleocytoplasmic shuttling via XPO1 (Exportin1). Reduced PALMD expression resulted in subcellular relocalization of RANGAP1 and XPO1, and nuclear arrest of the XPO1 cargoes p53 and p21. This indicates an important role for PALMD in nucleocytoplasmic transport and consequently in gene regulation because of the effect on localization of transcriptional regulators. Changes in EC responsiveness on loss of PALMD expression included failure to form a perinuclear actin cap when exposed to flow, indicating lack of protection against mechanical stress. Loss of the actin cap correlated with misalignment of the nuclear long axis relative to the cell body, observed in PALMD-deficient ECs, Palmd(-/-) mouse aorta, and human aortic valve samples derived from patients with calcific aortic valve stenosis. In agreement with these changes in EC behavior, gene ontology analysis showed enrichment of nuclear- and cytoskeleton-related terms in PALMD-silenced ECs.Conclusions: We identify RANGAP1 as a PALMD partner in ECs. Disrupting the PALMD/RANGAP1 complex alters the subcellular localization of RANGAP1 and XPO1, and leads to nuclear arrest of the XPO1 cargoes p53 and p21, accompanied by gene regulatory changes and loss of actin-dependent nuclear resilience. Combined, these consequences of reduced PALMD expression provide a mechanistic underpinning for PALMD's contribution to calcific aortic valve stenosis pathology.
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